Questions of a newcomer

1. The next CPU architecture from Intel, called "Haswell" doesn't have a definite release date but most estimates put it around mid-year. The next AMD CPU series will be Steamroller, again no official release date but estimated late Q3 or early Q4.

2. For a mainstream user running two CPU's is pointless and way too expensive. This capability is only available at the very high end of the market, and would require Xeon processors that are $1000+ a piece. Only real application for this kind of hardware would be large scale servers or basically super computers.

3. Next to none. RAM above 1600Mhz isnt worth it and the minimal performance difference isnt worth the increased cost to achieve that speed. If you have a very specific application or usage that can will be dictated by RAM speed, then its worth it, but for pretty much every other usage stick with 1600Mhz.

4. Not really, just to justify having four cards in SLI/Crossfire would require an ungodly amount of money to be spent on monitors and the rest of the rig. Also as you add on more cards, you get less of a performance gain per card, so most people dont go beyond two GPU's.

5. Not necessarily, it all depends on what your going to do with this system.Water-cooling isnt dangerous either, if you get good quality parts and research on how to put them together it will be quite reliable.

6. Depends if your smart enough to plan ahead. The main considerations are how much power you will need and PCI-E bandwidth, as well as having a case and mobo that are physically large enough to handle the cards.

Im under the impression you think that building a PC is overly complicated and will involve a ton of money. If its just gaming your after, you can build a top of the line rig for about $1500, same with Video editing. If you want both you will have to spend closer to $2000.

1. the intel CPU releases follow a tick-tock sequnce, with Haswell architecture being the next "tick", supposedly coming out this year.

2. 12 logical cores means 12 threads, translating to 2 triple core processorswith multi-threading. you could probably squeeze out a little life by disabling hyper-threading in the bios.

3. drop down to 16GB, that's too much. RAM is not a data bottleneck, so it can only affect AMD APU noticeably.

4. it's better to stick with 1 GPU and get another when you need more performance, by that time, the same gpu to sli has become cheap.

5. water cooling is unnecessary for a first build. it's needed more in high performance servers and extreme gaming rigs.

6. it's as difficult as installing drivers, putting another gpu in, connecting them, and turning on.

EDIT: fixed wording for chalk

OP:
watch these to begin your journey into the world of computer building:
1. http://www.youtube.com/watch?v=lPIXAtNGGCw
2. http://www.youtube.com/watch?v=d_56kyib-Ls
3. http://www.youtube.com/watch?v=RxaVBsXEiok

My decidedly mid-range gaming system with a triple radiator water loop begs to differ  
I would amend "enthusiast" into that.
Water-cooling is often done for the hell of it, I certainly don't need the performance it offers but I just want water-cooling in my rig.

True on all accounts, but we shouldn't overwhelm a noob, let's start with the basic knowledge, such as his expectation of a complex way of building.

OP:
watch these to begin your journey into the world of computer building:
1. http://www.youtube.com/watch?v=lPIXAtNGGCw
2. http://www.youtube.com/watch?v=d_56kyib-Ls
3. http://www.youtube.com/watch?v=RxaVBsXEiok

YOLO, might as well, but it is a little much for a first time builder

as with the rest, no to dual CPUs, no to >1600mhz ram, let alone needing any more than 8gb unless you're doing something far more intensive than gaming.

as for GPU; stick with one GPU for a single 1080p monitor build, 2 GPUs for a single 1440p monitor or 3x1080p monitors, and 3 beyond that.

if you're going for a custom water-loop, honestly, it's better that you build yourself, and familiarize with it because you're going to need to maintain it regularly. those liquid needs replacing and the loop needs to be checked for rust and algae. this equates to some regular spending for maintenance if you decide to take it to a shop, more than you would on your own. if all that is too much a hassle, air-cooling is still a very good option.

Erm, is there not a fairly large risk I will dump water all over my shiny new components?  

it's unlikely, but you should leave water cooling for another day, it takes extra research.

even if you accidentally spilled liquid, the liquid that you use would be nonconducting.

as long as the PC isn't on (it shouldn't) not too huge a problem. merely several hours to a day or two waiting for the liquid to evaporate. plus, leaking should always be expected when you test out the loop. best case scenario, everything is air tight in one go.

for a first timer, i share my views with lxgoldsmith. you're looking to invest some time, effort and money with a custom water loop. some have the tenacity to keep up with it over time (manofchalk), others don't (me). depends how massively big of an enthusiast they are.

Depends where that water has come from. If its been in the loop for a while and spills, then it will conduct since the metals of the loop will have gradually seeped into the water, regardless if it was de-ionized when it went in. If its straight from the bottle or has only been in the loop briefly it should be fine. But regardless, if water gets on the mobo or other PCB's you have to mop it up and wait a bit for it to dry.

There is the possibility of your parts getting drenched, but pretty much all of them involve user error. If you research what your doing and are diligent when building the loop and do it properly, you wont have any issues.

But yes, it is not outright necessary for your rig. Whether getting your feet wet is in your future will depend on how much time and effort you are willing to commit. Because coming from someone who added a T-Line to his loop less than an hour ago, it requires a lot of both.

+1